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Next: raid10.. how many drives can fail and still have ..
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External
Since: Dec 20, 2007
Posts: 2
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(Msg. 1) Posted: Thu Dec 20, 2007 3:18 pm
Post subject: How do I arrange drives.
Archived from groups: comp>sys>ibm>pc>hardware>storage (more info?)
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I need about 10 Terabytes of storage space.
I see that there are 1 Terabyte disks available.
I'm new to RAID, so please...
As I understand it there are different ways to configure drives in a
raid for redundancy...
If there are 8 bites per byte and one bit for parity and / or
redundancy, then do I need 9 drives to have a full 10 Terabytes? or is
that only 8 terabytes?
In this configuration if one drive fails it can be replaced and its
contents would be rebuilt?
Is that a function of the RAID controller?
Do RAID systems always use SCSI drives?
Care to point me in the right direction? |
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External
Since: Nov 07, 2003
Posts: 1692
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(Msg. 2) Posted: Thu Dec 20, 2007 11:47 pm
Post subject: Re: How do I arrange drives. [Login to view extended thread Info.]
Archived from groups: per prev. post (more info?)
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Previously SpreadTooThin <bjobrien62.TakeThisOut@gmail.com> wrote:
> I need about 10 Terabytes of storage space.
> I see that there are 1 Terabyte disks available.
> I'm new to RAID, so please...
> As I understand it there are different ways to configure drives in a
> raid for redundancy...
> If there are 8 bites per byte and one bit for parity and / or
> redundancy, then do I need 9 drives to have a full 10 Terabytes? or is
> that only 8 terabytes?
8. And take into account that HDD manufacturer use correct SI units,
so that TB would be 1,000,000,000,000 Bytes.
You need 11 drives for a 10TB RAID5. You need 12 drives for a
10TB raid6.
> In this configuration if one drive fails it can be replaced and its
> contents would be rebuilt?
Yes.
> Is that a function of the RAID controller?
Among other things, it should be able to do this.
> Do RAID systems always use SCSI drives?
No.
> Care to point me in the right direction?
If speed is not an issue, you may wanto to condider software
RAID. If speed is an issue, get a 12 port SATA controller.
Currently 3ware and arcea seem to have the best hardware,
and 3ware seem to have the best support and drivers. Stay
away from Adaptec, they produce high-priced trash.
Consider, e.g., these controllers:
http://www.3ware.com/products/serial_ata2-9000.asp
http://www.3ware.com/products/serial_ata2-9650.asp
For hardware RAID you also want to get a spare controller,
since thay can fail as well. For software RAID, that is not
a concern and a software RAID array can typically be used
on an entirely different computer (with enough controller ports)
without loss of ddata. At least under Linux it is not an issue
at all.
As to redundancy, you may consider RAID6, which can survive a
2-disk loss without loss of data, but costs you the capacity
of 2 disks. Also make sure you have a spare disk handy,
operating a RAID array without redundancy is dangerous.
Arno |
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External
Since: Dec 20, 2007
Posts: 2
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(Msg. 3) Posted: Fri Dec 21, 2007 9:22 am
Post subject: Re: How do I arrange drives. [Login to view extended thread Info.]
Archived from groups: per prev. post (more info?)
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On Dec 20, 4:47 pm, Arno Wagner <m... DeleteThis @privacy.net> wrote:
> Previously SpreadTooThin <bjobrie... DeleteThis @gmail.com> wrote:
> > I need about 10 Terabytes of storage space.
> > I see that there are 1 Terabyte disks available.
> > I'm new to RAID, so please...
> > As I understand it there are different ways to configure drives in a
> > raid for redundancy...
> > If there are 8 bites per byte and one bit for parity and / or
> > redundancy, then do I need 9 drives to have a full 10 Terabytes? or is
> > that only 8 terabytes?
>
> 8. And take into account that HDD manufacturer use correct SI units,
> so that TB would be 1,000,000,000,000 Bytes.
>
> You need 11 drives for a 10TB RAID5. You need 12 drives for a
> 10TB raid6.
>
> > In this configuration if one drive fails it can be replaced and its
> > contents would be rebuilt?
>
> Yes.
>
> > Is that a function of the RAID controller?
>
> Among other things, it should be able to do this.
>
> > Do RAID systems always use SCSI drives?
>
> No.
>
> > Care to point me in the right direction?
>
> If speed is not an issue, you may wanto to condider software
> RAID. If speed is an issue, get a 12 port SATA controller.
> Currently 3ware and arcea seem to have the best hardware,
> and 3ware seem to have the best support and drivers. Stay
> away from Adaptec, they produce high-priced trash.
>
> Consider, e.g., these controllers:http://www.3ware.com/products/serial_ata2-9000.asphttp://www.3ware.com/products/serial_ata2-9650.asp
>
> For hardware RAID you also want to get a spare controller,
> since thay can fail as well. For software RAID, that is not
> a concern and a software RAID array can typically be used
> on an entirely different computer (with enough controller ports)
> without loss of ddata. At least under Linux it is not an issue
> at all.
>
> As to redundancy, you may consider RAID6, which can survive a
> 2-disk loss without loss of data, but costs you the capacity
> of 2 disks. Also make sure you have a spare disk handy,
> operating a RAID array without redundancy is dangerous.
>
> Arno
Thanks very much.
I am also reading:
http://en.wikipedia.org/wiki/RAID
I don't understand the diagrams that represent the bits and how they
are stored except for RAID0.
RAID0 has bits 1 to 8.. (No Parity) but from there on in I don't
understand the notation for the bits and parity.
Why don't they only show A1 to A8 on all the raid configurations? are
the higher bits encoded somehow? >> Stay informed about: How do I arrange drives. |
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External
Since: Nov 07, 2003
Posts: 1692
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(Msg. 4) Posted: Fri Dec 21, 2007 6:31 pm
Post subject: Re: How do I arrange drives. [Login to view extended thread Info.]
Archived from groups: per prev. post (more info?)
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Previously SpreadTooThin <bjobrien62.RemoveThis@gmail.com> wrote:
> On Dec 20, 4:47 pm, Arno Wagner <m....RemoveThis@privacy.net> wrote:
>> Previously SpreadTooThin <bjobrie....RemoveThis@gmail.com> wrote:
>> > I need about 10 Terabytes of storage space.
>> > I see that there are 1 Terabyte disks available.
>> > I'm new to RAID, so please...
>> > As I understand it there are different ways to configure drives in a
>> > raid for redundancy...
>> > If there are 8 bites per byte and one bit for parity and / or
>> > redundancy, then do I need 9 drives to have a full 10 Terabytes? or is
>> > that only 8 terabytes?
>>
>> 8. And take into account that HDD manufacturer use correct SI units,
>> so that TB would be 1,000,000,000,000 Bytes.
>>
>> You need 11 drives for a 10TB RAID5. You need 12 drives for a
>> 10TB raid6.
>>
>> > In this configuration if one drive fails it can be replaced and its
>> > contents would be rebuilt?
>>
>> Yes.
>>
>> > Is that a function of the RAID controller?
>>
>> Among other things, it should be able to do this.
>>
>> > Do RAID systems always use SCSI drives?
>>
>> No.
>>
>> > Care to point me in the right direction?
>>
>> If speed is not an issue, you may wanto to condider software
>> RAID. If speed is an issue, get a 12 port SATA controller.
>> Currently 3ware and arcea seem to have the best hardware,
>> and 3ware seem to have the best support and drivers. Stay
>> away from Adaptec, they produce high-priced trash.
>>
>> Consider, e.g., these controllers:http://www.3ware.com/products/serial_ata2-9000.asphttp://www.3ware.com/products/serial_ata2-9650.asp
>>
>> For hardware RAID you also want to get a spare controller,
>> since thay can fail as well. For software RAID, that is not
>> a concern and a software RAID array can typically be used
>> on an entirely different computer (with enough controller ports)
>> without loss of ddata. At least under Linux it is not an issue
>> at all.
>>
>> As to redundancy, you may consider RAID6, which can survive a
>> 2-disk loss without loss of data, but costs you the capacity
>> of 2 disks. Also make sure you have a spare disk handy,
>> operating a RAID array without redundancy is dangerous.
>>
>> Arno
> Thanks very much.
> I am also reading:
> http://en.wikipedia.org/wiki/RAID
> I don't understand the diagrams that represent the bits and how they
> are stored except for RAID0.
These are confusing, I agree.
> RAID0 has bits 1 to 8.. (No Parity) but from there on in I don't
> understand the notation for the bits and parity.
It is not done on bit-level, but rather sector level or larger.
> Why don't they only show A1 to A8 on all the raid configurations? are
> the higher bits encoded somehow?
See above.
Arno >> Stay informed about: How do I arrange drives. |
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External
Since: Nov 10, 2003
Posts: 1690
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(Msg. 5) Posted: Sun Dec 23, 2007 10:51 pm
Post subject: Re: How do I arrange drives. [Login to view extended thread Info.]
Archived from groups: per prev. post (more info?)
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Arno Wagner wrote in news:5t0d85F1bcrthU1@mid.individual.net
> Previously SpreadTooThin <bjobrien62.RemoveThis@gmail.com> wrote:
> > I need about 10 Terabytes of storage space.
> > I see that there are 1 Terabyte disks available.
>
> > I'm new to RAID, so please...
>
> > As I understand it there are different ways to configure drives in a
> > raid for redundancy...
>
> > If there are 8 bites per byte and one bit for parity and / or
> > redundancy, then do I need 9 drives to have a full 10 Terabytes? or is
> > that only 8 terabytes?
>
> 8. And take into account that HDD manufacturer use correct SI units,
> so that TB would be 1,000,000,000,000 Bytes.
>
> You need 11 drives for a 10TB RAID5. You need 12 drives for a
> 10TB raid6.
>
> > In this configuration if one drive fails it can be replaced and its
> > contents would be rebuilt?
>
> Yes.
>
> > Is that a function of the RAID controller?
>
> Among other things, it should be able to do this.
>
> > Do RAID systems always use SCSI drives?
>
> No.
>
> > Care to point me in the right direction?
>
> If speed is not an issue, you may wanto to condider software
> RAID. If speed is an issue, get a 12 port SATA controller.
> Currently 3ware and
> arcea
The babblebot moron consistently can't even spell the name right.
> seem to have the best hardware,
> and 3ware seem to have the best support and drivers.
> Stay away from Adaptec, they produce high-priced trash.
>
> Consider, e.g., these controllers:
> http://www.3ware.com/products/serial_ata2-9000.asp
> http://www.3ware.com/products/serial_ata2-9650.asp
>
> For hardware RAID you also want to get a spare controller,
> since thay can fail as well. For software RAID, that is not
> a concern and a software RAID array can typically be used
> on an entirely different computer (with enough controller ports)
> without loss of ddata. At least under Linux it is not an issue
> at all.
>
> As to redundancy, you may consider RAID6, which can survive a
> 2-disk loss without loss of data, but costs you the capacity
> of 2 disks. Also make sure you have a spare disk handy,
> operating a RAID array without redundancy is dangerous.
Yeah, far more dangerous then just using harddrives.
>
> Arno >> Stay informed about: How do I arrange drives. |
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